Which organ is responsible for dehydration and compaction of indigestible materials?

Large intestine

Explanation:

After the completion of digestion process in the small intestine, the indigestible residual materials are passed to the large intestine.

The large intestine serves three primary functions -

Absorption of water and electrolytes Production and absorption of vitamins Formation and propelling of feces accomplishing their removal through the rectum.

When water gets absorbed, the indigestible materials get dehydrated and during feces formation they are compacted and then eliminated through the rectum.